Ore flotation is a process for separating finely ground valuable minerals from their associated gaugue or for separating valuable components one from the other. The process is based on the affinity of properly prepared surfaces for air bubbles. In froth flotation, a froth is formed by introducing air into a pulp of the finely divided ore and water containing a frothing agent. Its chief advantage is that it is a relatively efficient operation at a substantially lower cost than many other processes.
Frothing agents are used to provide a stable flotation froth, persistent enough to facilitate the mineral separation, but not so persistent that it cannot be broken down to allow subsequent processing. The most commonly used frothing agents are pine oil (an impure terpineol, C.sub.10 H.sub.17 OH); creosote and cresylic acid; and alcohols such as 4-methyl-2-pentanol, polypropylene glycols and ethers.
In addition to the frothing agents, the aqueous ore slurry being processed will contain a selected collector which has particular selectivity for the mineral values that are desired to be recovered by froth flotation. Current theory states that the flotation separation of one mineral species from another depends upon the relative wettability of surfaces. Typically, the surface free energy is purportedly lowered by the adsorption of heteropolar surface-active agents. The hydrophobic coating thus provided acts in this explanation as a bridge so that the particle may be attached to an air bubble. The practice of this invention is not, however, limited by this or other theories of flotation. Thus, the slurry containing ore and frother is conditioned with the proper collector and subjected to froth flotation by introducing air into such slurry. A froth is generated by action of the air introduced and the frother. The desired mineral values coated with the selected collector entrap the air bubbles and are levitated as a result, rising into the froth layer which overflows the flotation device. The operation is continued until further build-up of levitated mineral values in the froth ceases. The mineral values recovered by froth flotation of the native ore is designated as the "rougher concentrate" and the residue is designated as the "rougher tails." Subsequently, the rougher concentrate may be subjected to additional froth flotation in one or more operations to provide what are termed "cleaner concentrates" and "cleaner tails." Some operations where the collector is itself a frother agent, it is possible to omit the addition of a frother per se, but in most operations a frother is essential, as is a collector.
Although the art is replete with collectors and frothers which find application in the various flotation processes, there continues a need for new and more efficient collectors and frothers which will either enhance recovery selectivity, or lower the costs involved in the flotation process.